The D634‑308C is a high‑flow, high‑response single‑stage direct‑drive servo valve in the D634 family. It uses a permanent magnet linear force motor to drive the spool directly—no pilot oil required. Integrated 24 VDC electronics with LVDT closed‑loop spool position feedback provide excellent linearity and repeatability, with dynamics largely independent of supply pressure. Spring‑centered for fail‑safe return to neutral on power loss. Calibrated for high flow + fast response, suited for demanding closed‑loop position/velocity/pressure control.1. General Description The D634‑308C is a high‑flow, high‑response single‑stage direct‑drive servo valve in the D634 family. It uses a permanent magnet linear force motor to drive the spool directly—no pilot oil required. Integrated 24 VDC electronics with LVDT closed‑loop spool position feedback provide excellent linearity and repeatability, with dynamics largely independent of supply pressure. Spring‑centered for fail‑safe return to neutral on power loss. Calibrated for high flow + fast response, suited for demanding closed‑loop position/velocity/pressure control. 2. Hydraulic Specifications Mounting: ISO 4401 Size 05 (NG10) Max working pressure (P, A, B): 350 bar (5,000 psi) T‑port pressure: 50 bar (without Y‑port); 350 bar (with Y‑port) Rated flow (Δp = 35 bar per land): 100 L/min (26.4 gpm) Maximum flow: approx. 190 L/min (50.2 gpm) Internal leakage: ≤ 0.9 L/min Fluid: Mineral oil (ISO 11158 / DIN 51524) Fluid temperature: −20 °C to +80 °C Filtration: ISO 4406 17/14/11 or better Weight: approx. 6.4 kg (14.1 lb) 3. Dynamic Performance (Typical) Step response (0 → 100% stroke): ≤ 16 ms −3 dB bandwidth: 70–80 Hz Hysteresis: < 0.4% of full scale Resolution: < 0.08% of full scale Null drift (60 K temp change): < 1.2% of full scale 4. Electrical Specifications Supply voltage: 24 VDC (18–32 VDC) Max operating current: 3.2 A Command signal (jumper selectable): ±10 V, ±10 mA, 4–20 mA Spool position feedback output: 0–10 VDC Connector: M18, 6 pins + PE, IP65 Ambient temperature: −20 °C to +60 °C EMC: CE compliant 5. Key Features High‑flow + high‑bandwidth direct drive: 100 L/min, fast step response Integrated LVDT closed‑loop: excellent accuracy and repeatability Pressure‑independent dynamics: stable across varying loads Low internal leakage: energy efficient for high‑flow systems Spring‑centered fail‑safe: safe shutdown on power loss 6. Applications High‑speed, high‑flow hydraulic axes Precision presses & heavy‑duty industrial machinery High‑performance injection molding & die‑casting Dynamic material testing & fatigue systems Closed‑loop control requiring both high flow and fast response 7. Wiring Definition Pin 1: +24 VDC Pin 2: Power ground Pin 3: Command signal (+) Pin 4: Command signal (−) Pin 5: Spool position feedback (0–10 VDC) Pin 6: Feedback ground PE: Protective earth Recommendation: Use shielded twisted‑pair cable for signals.